Process of producing coeroxenol esters



Patented Aug. 16, 1938 UNlTED STATES PROCESS OF PRODUCING. coERoxENoL ESTERS Thomas A. Cassidy, Brooklyn, N. Y., a's'signor to Wilmot and Cassidy, Inc., Brooklyn, N. Y., a corporation of New York No Drawing. Original application July 24,1934,

Serial No. 736,631. Divided and this application October 3, 1936, Serial No. 103,911

8 Claims.

This application for patent is a division of an application filed by me July 24, 1934, Serial No. 736,631, which is a continuation in part of an application for patent filed by me August 23, 1932, Serial No. 630,087.

The present invention relates to a process for producing fluorescent dyes soluble in high boiling aliphatic and aromatic hydrocarbons, particularly lubricating oil, and more particularly to certain dyes of the heterocyclic group containing oxygen in the ring.

In marketing petroleum products such as motor fuels, lubricating oils, etc, it is customary to add certain dyes to these products in order that the purchasers may distinguish between the different brands. In some cases several manufacturers use the same color or different shades of the same color, thereby making it difficult for the purchaser to know whether or not he is getting the products he orders. The producers, who are marketing artificially colored products, are loath to change the colors of their products, and in some cases it is impracticable to do, as certain colors are now Widely used to designate certain qualities. Again,it is not desirable to color certain petroleum products, as such coloring would destroy their sales value, the products being graded by their natural colors. 7

One way to distinguish from one anotherdifferent brands having the same color is to impart fluorescence of different hues to these products, thereby giving them distinguishing characteristics without substantially altering their colors as viewed by transmitted light. In the case of lubricating oils, imparting a green fluorescence actually enhances the value.

There are many known dyestuffs which'will impart fluorescence to alcohol and water and some are known to be soluble in, and impart fluorescence to, lighter petroleum hydrocarbons; but few, if any, are known to be soluble in, and adapted to impart fluorescence to, lubricating oils and which at the same time are known to be stable to light, heat and storage-to be unaffected by metals, to be'completely neutral in reaction and not to impart to such oils any qualities which would make them commercially impracticable.

Certain dyestuffs'of the heterocyclic group containing oxygen in the ring which are free from nitrogen and sulphur, namely, organic compounds of the coeroxene class (by which term I mean to include coeroxene, its derivatives and substitution products) I have found to be soluble in and effective to impart fluorescence of different shades of green and of varying degrees of intensity to both aliphatic and aromatic hydrocarbons.

So far as I know, none of the dyestuifs of the class mentioned have ever been added to comin and impart fluorescence thereto, as above stated, but that they possess the other qualities, above enumerated, necessary to render their use for this'purpose commercially practicable. I have, for example, found that dimethyl 6,12- -5 coeroxenolaceta'te, when produced by the process herein-afterdescribed, meets all the most exacting requirements. Y

However, known processes for producing organic Compounds of the coeroxene class do not l o produce these compounds, including the specific compound just above mentioned, in a form entirelyacceptable for addition to lubricating oils. The present invention comprises an improved method of producing these compounds, parr5 ticularly applicable to the production of 6,12- dimethyl coeroxenol acetate and other substituted coeroxenol esters, whereby a high yield of the compound may be produced in its purest state and in a form which renders its use as an addigo tion to lubricating oils highly efficient to produce the desired green fluorescence and ineffective to impart to the oil any undesirable characteristics. 1 In manufacturing the improved product I proceed as follows, it being understood that those skilled in the art may deviate, without the exercise of invention, from the precise details of the prescribed steps, which are preferable rather than mandatory. It will also be understood that the described specific. process is intended for the production of 6,12-dimethyl coeroxenol acetate and that obvious modifications of the process are necessary for the production of other organic color compounds of the coeroxene class. "To a molten mass comprising 220 pounds of 1 paracresol (or a meta or para'substituted phenol) and 150 pounds of phth-alic anhydride are added 90 pounds of concentrated sulfuric acid or other condensing agent such as phosphorous pentoxide v zinc chloride or stannic chloride. 4

1 The mix is then heated with agitation to about 160 C. and maintained at that temperature for about five hours. At the conclusion of this heating step the mass is dumped into (say) 300 gallons of water to which is added 100 pounds of caustic soda or any other strong base such as caustic potash or'lithium hydroxide. This mix is then boiled for about one hour and the indi-substituted 2,7- or 3,6-fiuoran produced by the procedure above described by or any obvious vari- 5' ation thereof) is added to 700 pounds of fuming sulfuric acid (oleum) at 20-25 TC. and the mix .iscontinuously agitated for about eight hours,

after which it is diluted by pouring into 1200 pounds of water to'which has been addedabout an equal weight of ice. The product is a sub stituted coeroxonol sulfate-specifically, following the precise procedure above described, a red solution of dimethyl 6,12-coeroxonol sulphate.' 1

' homologues, produce a green fluorescence when dissolved in aliphatic or aromatichydrocarbons. For instance, dimethyl 6,12-coeroxenol, its isomers and homoiogues may be used as well as the acetates, benzoates, phthalates or any organic acid ester, of dimethyl 6,12-coer0xenol and its isomers or homologues. Dimethyl 6,12 -c0- eroxenol is not as stable to heat and light as are dimethyl 6,12-coerox'ene and the derivatives and substitution products ofdimethyl 6,12-coeroxeno1 which will impart a fluorescence to aliphatic and aromatic hydrocarbons. However, I believe it to be impossible, by the employment of any known process, to secure a commercially economical yield or to secure a product of satisfactory purity, strength, color, or stability to heat or in storage. The following procedure for obtaining the dimethyl 6,12-coeroxenol acetate mentioned has been found to overcome all the objections inherent in known processes.

After the coeroxonol basein the specific example the dimethyl 6,12-coeroxonol base-is obtained, pounds ofthe same are mixed with 400 pounds of water, 40 pounds of caustic soda or other strong base and 280 pounds of pyridine, or equivalents thereof, e. g., methyl pyridines (picolines), dimethyl pyridenes (lutidines) or other organic solvents soluble in water that do not react with acetic anhydride, such as acetone and dioxan. The mixture is heated to 90 C. and agitated.

Thereafter is added 30 pounds of zinc dust or iron powder. The entire mixture is then agitated for about two hours at 90 C. and cooled to 30 C.

after which there is added slowly a suitable acid esterifying agent, such as acetic anhyride, propionic anhydride, butyric anhyride or benzoyl chloride. The mixture is maintained for about two hours at 30 C. and is added to 400 gallons of water, filtered and the product washed and dried. Assuming the addition of the preferred acid esterifying agent-acetic anhydridethe yield is 70-100 pounds of dimethyl6,l2 coeroxenol. acetate.

The pyridine orequivalent bases play a dual. role, one that of acting as a solvent for the coeroxonol base to facilitate reduction and the other What I claim and desire to protect by Letters Patent is? 1. The process of producing a substituted coeroxenol ester of high purity and yield and suitable for addition to lubricating oil to impart fluorescence thereto which comprises reducing a substituted coeroxonol in an alkaline medium containing an organic solvent soluble in water and that does not react with the subsequently added esterifying agent and then esterifying.

2, The process of producing dimethyl 6,12- coeroxenol acetate of high purity and yield which comprises reducing dimethyl 6,12-coeroxonol in an alkaline medium containing an organic solvent soluble in water and that does not react with acetic anhydride and then esterifying by addition of acetic anhydride.

3. The process of producing dimethyl 6,12- coeroxenol acetate of high purity and yield which comprises treating dimethyl 6,12-coeroxonol with pyridine, caustic alkali and zinc dust and ester ifying by the addition of acetic anhyride.

4. The process of producing a substituted coeroxenol ester of high purity and yield which comprises treating a di-substituted fluoran with sulphuric acid and thereby producing a substituted coeroxonol sulphate, precipitating the substituted coeroxonol base, reducing the coeroxonol base in an alkaline medium containing an organic solvent soluble in water and that does not react with the subsequently added esterifying agent, and then esterifying to producethe substituted coeroxenol ester.

5. The process of producing a substituted coeroxenol ester of high purity and yield which comprises treating a di-substituted fiuoran with sulphuric acid and thereby producing a substituted coeroxonol sulphate, precipitating the substituted coeroxonol base, reducing the coeroxonol base in an alkaline medium containing pyridine and esterifying by the addition of acetic anhydride.

6.'The process of producing dimethyl 6,12- coeroxenol acetate of high purity and yield which comprises treating dimethyl 2,7-fiuoran with sulfuric acid and thereby producing dimethyl 6,12- coeroxonol sulphate, precipitating the dimethyl 6,12-coeroxonol base, reducing said base in admixture with water, caustic alkali and pyridine,

and esterifying by the addition of acetic anhydride.

7. The process of producing dimethyl 6,12- coeroxenol acetate of high purity and yield which comprises melting together paracresol phthalic anhydride, adding sulphuric acid, treating the mix with caustic alkali to thereby produce as an intermediate product dimethyl 2,7-fluoran, treating said intermediate product with sulfuric acid and thereby producing dimethyl 6,12- coeroxonol sulphate, precipitating the dimethyl 6,12-coeroxonol base, reducing said base in admixture with water, caustic alkali and pyridine, and esterifying by the addition of acetic anhydride. V

8. The process of producing dimethyl 6,12- coeroxenol acetate of high purity and yield which comprises treating approximately 220 parts of paracresol and parts of phthalic anhydride with a condensing agent, and treating the re- .sulting mixture with caustic alkali to thereby produce dimethyl 2,7-fiuoran, treating said intermediate product with sulphuric acid to pro- 1 duce dimethyl 6,12-coeroxonol sulphate, precipitating the dimethyl 6,12-coeroxonol base, reducing said base in admixture with water, caustic alkali and pyridine, and esterifying by the addition of acetic anhydride.

THOMAS A. CASSIDY.

and 

